Nordic Optical Telescope (NOT). Dome of the 2.6-metre NOT at the Roque de los Muchachos observatory on La Palma in the Canary Islands. This telescope observes at optical and infrared wavelengths. Its 11.1-metre diameter dome stands at an altitude of 2382 metres. The NOT is jointly operated by institutions in Denmark, Finland, Norway, Sweden and Iceland. The observatory is an ideal site because the high altitude and the clear air above it mean that atmospheric distortions to incoming light are minimised.